TH400 Transmission

[MrDerek]

Hello All. Well I finally put my 70 Chevelle on the road today. Runs great. Only one problem. My 400 trans will not shift out of 1st gear. It pulls strong and will go in reverse. I even put my foot in that 454 and wow!! Any help would be appreciated. I know nothing about transmissions. Thanks

[Berg]

could be a few different things. I'm not that great with automatic transmissions but it could have something to do with the governor on the side of the transmission in the rear. It is located under a little sheet metal cover with a wire band holding it to the case. It could also be a problem with the valve body or worse yet, could have a broken shell inside the trans itself. Even a cut seal wouldn't let it build pressure. They basically work on hydraulic pressure so any thing like that could keep it from working. Of course you could have a trans with a full manual valve body if someone raced it out once before. I got one of those and it won't shift on its own at all. It has to be put into each gear. It is possible to actually take off in 2nd gear with it. You can't run a kickdown with it for obvious reasons. Do you know the history on the transmission? Check the fluid level again also because after you install it and all the fluid goes into all the passages you can top it off and try from there.

[jays 1971]

I had a similar issue with mine when I got it except my gears were all changed around. The trans was in drive but couldn't leave first. 1st, 2nd gear positions worked normal except revved to like 2500rpm before moving then came down to normal. Much like slowly easing off the clutch would do in a manual. Turned out when the previous owner put the shift kit in he put one of the check balls in the wrong spot. Only figured it out when I pulled it apart to invstigate and saw a dent in the retaining plate. Just one of many things but possible depending on its history.